Spider wasp
Wasps in the family Pompilidae are commonly called spider wasps or pompilid wasps.1 The family is cosmopolitan, with some 5,000 species in six subfamilies.2 All species are solitary, and most capture and paralyze prey, though members of the subfamily Ceropalinae are cleptoparasites of other pompilids, or ectoparasitoids of living spiders.3 In South America, species may be referred to colloquially as marabunta or marimbondo, though these names can be generally applied to any very large stinging wasps. Furthermore, in some parts of Venezuela and Colombia, it is called matacaballos, or "horse killers", while in Brazil some particular bigger and brighter species of the general marimbondo kind might be called fecha-goela, or "throat locker". Morphology Like other strong fliers, pompilids have a thorax modified for efficient flight. The metathorax is solidly fused to the pronotum and mesothorax; moreover, the prothorax is best developed in Pompilidae and Scoliidae because wasps in these families use their forelegs to dig. Pompilids typically have long, spiny legs; the hind femur is often long enough to reach past the tip of the abdomen. The tibiae of the rear legs usually have a conspicuous spine at their distal end. The first two segments of the abdomen are narrow, giving the body a slender look. The pompilid body is typically dark (black or blue, sometimes with metallic reflections), but many brightly colored species exist. From a lateral view, its pronotum looks rectangular and it extends back to the tegulae, near the base of the wings. Most species are macropterous (having long wings), but a few brachypterous (short-winged) and apterous (no wings) species are known.2 Spider wasps are best distinguished from other vespoid wasps in having (in most species) a transverse groove bisecting the mesopleuron (the mesepisternal sclerite, a region on the side of middle segment of the thorax above the point where the legs join). Like other Vespoidea, they have antennae with 10 flagellomeres in the female and 11 in the male. Most Pompilidae have straight inner eye margins. The hind wings do not have a distinct claval lobe, but they have a distinctive jugal lobe. The hind leg has a tibial spur with a tuft or row of fine hairs. The legs are long and slender with the tips of the tibia (metatibia) long enough to extend beyond the tip of the abdomen (metasoma). Sexual dimorphism is not pronounced, although females are often larger than the males. Coloration and wing appearance vary greatly among the many species. General coloration is aposematic (warning off predators), generally based on black, often with markings of orange, red, yellow, or white.3 Larvae can also be identified by physical examination. Spider wasps are solitary wasps that use a single spider as a host for feeding their larvae. They paralyze the spider with a venomous stinger. Once paralyzed, the spider is dragged to where a nest will be built – some wasps having already made a nest.5 A single egg is laid on the abdomen of the spider, and the nest or burrow is closed. Spider wasps protect their nests by putting dead ants into the outermost chamber, the chemicals within deterring predators. The size of the host can influence whether the wasp's egg will develop as a male or a female; larger prey yield the (larger) females.8 A complex set of adult behaviors can then occur, such as spreading soil or inspecting the area, leaving the nest site inconspicuous. When the wasp larva hatches, it begins to feed on the still-living spider. After consuming the edible parts of the spider, the larva spins a silk cocoon and pupates, usually emerging as an adult the next summer. Some ceropalines lay the egg on a still-active spider, where it feeds externally on hemolymph. In time, that spider will die, and the mature wasp larva will then pupate. Distribution Currently, the Pompilidae are split unequally into six subfamilies throughout most of the world. Ceropalinae and Notocyphinae contain two genera each and occur in Central and South America and the Oriental region. The Epipompilinae contain a single genus and occurs in the Neotropics, the Australasian region, and the Afrotropical region. The Ctenocerinae contain two genera in the Neotropics, four in Australia and 11 in Africa. Pepsinae and Pompilinae are the most diverse, and the remaining genera are split between them. Ecology and behavior Category:Hymenoptera